Method of treating milk.



J. L. GUUUHER.

METHOD OF TREATING MILK.

APPLICATION FILED SBPT.1B,1906

Patented May 18, 1909. 2 sHEnTs-snnnT 1.

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J. L. GOUGHER.

METHOD OF TREATING MILK.

APPLICATION FILED 315F118, 1906.

92%, Patented May 13, 1909. 2 sums-5mm 2.

HIM 1| nnrrnn srarns Parana orrren JAMES L. GOUCHER, OF NEW YORK, N.'Y., ASSIGNOR TO GOUCHER ELECTRIC PURIFYING CO., OF NEW YORK, N. Y., ACORPORATION OF NEW YORK.

METHOD OF TREATING- MILK.

Specification of Letters Patent.

Patented May 18, 1909.

Application filed September 18, 1906. Serial No. 335,131.

T 0 all whom it may concern:

Be it known that I, JAMEs IJ- GoUonER, a citizen of the United States,and a resident of New York, in the county of New York and State of NewYork, have invented certain new and useful Improvements in Methods ofTreating Milk, of which the following is a specification.

This invention relates to a method of treat-- ing milk to purify thesame, the main object of the invention being to improve the quality ofthe liquid treated, which is brought about, among other things, bydestroying the colonies of bacteria which are always present in milk inits ordinary state and which are propagated rapidly under the ordinaryconditions surrounding the handling, shipment and use of milk which as aliquid food normally carries solid in suspension.

The destruction of bacteria in milk, particularly by electrical action,has been attempted heretofore by others, who have obtained good results,but in none of the processes with which I am familiar has any one, sofar as I am aware, succeeded in eliminating from milk all orsubstantially all of the bacteria normally found therein. This I believehas been due partly to the fact that the proper treatment of milk byelectricity for the purpose of destroying bacteria therein has not beenfully understood, and partly to the fact that no sufficient provisionhas been made for preventing the contamination of partly purified milkby bacteria in the air surrounding such milk.

In order to destroy bacteria in milk quickly and without in other waysinjuriously affecting the quality or taste of the milk, I have found byexperiment that it is important to subject the milk to the action ofelectricity in such a manner as to avoid overheating or cooking themilk, it being preferable to employ a current of moder ately highvoltage and of small amperage, which will destroy the bacteria in themilk quickly, but will otherwise have little or no effect upon the milkso treated. It is most advantageous to make use of an alternatingcurrent of electricity, as the purification of the milk is accomplishedmore quickly than with the use of direct current.

The destruction of bacteria in milk by electrical action, I believe asthe result of my experiments, to be due both to the direct action ofelectric current, particularly alternating current, upon the colonies ofbacteria in the milk, and to the formation and release of ozone gas fromthe liquid, which gas when so formed and liberated exerts in the nascentstate a very strong sterilizing action upon the whole body of liquidwith which it comes in contact, and destroys instantly all colonies ofbacteria through which the gas passes. When milk exposed to the air issubjected to the action of an alternating current of suitable voltageand amperage, the number of colonies of bacteria in each cubiccentimeter of milk will be reduced far below the number ordinarily foundin the best grades of milk on the market, and when the action takesplace in the manner hereinafter described in detail the number ofcolonies in each cubic centimeter may be re duced to not more than a fewhundred. I have found, however, that it is impossible under ordinaryworking conditions to eliminate all of the bacteria from milk when thewhole body of milk is exposed to the air throughout the whole of theperiod during which it is subjected to the action of the nate all orsubsta11tiallyall colonies of bacteria it is necessary, at least duringthe final treatment of a given quantity or stream of milk, to inclosethe milk or stream in such a manner that it will be out of contact withthe air, and while so out of contact with the air I subject it to theaction of an electric current for the purpose of destroying such finalcolonies of bacteria as may have been propagated and may still remain inthe milk and such other colonies as may have been introduced into themilk by contact of the air with the surface of the milk during the earlystages of the treatment. By subjecting milk first to electrical actionin contact with the air and afterward to electrical action out ofcontact with the air, and particularly when the electric current iscaused to flow through a stream of milk at many points in the lengththereof and in the direction transverse to the flow of the stream, Ihave found that all bacteria can be eliminated from milk and that themilk so purified can be bottled for use by the consumer entirely free ofbacteria. Such milk, I have also found, will remain fresh and sweet fora very much longer period of time than the best untreated milk that Ihave found, this being an important factor in the problem of I obtainingfrom a distance an adequate milk 1 supply for a large city.

electric current, and that in order to elimi- Other features of myimproved process of purifying milk will be hereinafter more fully setforth, the various features of the invention being illustrated in theaccompanying drawings, in which- Figure 1 is a combined plan anddiagrammatic view of an embodiment of the invention in a milk-treatingapparatus and electrical connections for carrying out the invention;Fig. 2 is a similar View of a modified type of milk-treating apparatus;Fig. 3 is a si e elevation of the main portions of the apparatus andassociated parts illustrating the supply-tank, the purifying apparatusand a series of receiving tanks; Fig. 4 is an enlarged transversesection of a portion of the apparatus, the section being taken in theline 44:, Fig. 3, looking in the direction of the arrow; Fig. 5 is asimilar view illustrating the apparatus at another point in its length,the section being taken in the line 55; Fig. 3 and Fig. 6 is an enlargedsectional side elevation of the delivery end of the milk-purifyingapparatus, illustrating the manner 1n which the milk is kept out ofcontact with the air during its final treatment and while beingdelivered to the receiving tanks.

Similar characters designate like parts in all the figures of thedrawings.

In carrying my invention into effect I prefer to employ as the vessel inwhich the milk is subjected to treatment a long trough such as 2, ofnon-conducting material, through which the milk may flow in a relativelylong stream after being delivered thereto from a suitable source ofsupply. This source of supply may be a tank, such as 3, having the usualstop-cock 4 for turning on and off the stream. The object of passing thestream through such a trough as that shown at 2 is to subject it totreatment at a considerable number of points, at each of which therewill be but a comparatively small body of milk to be acted upon at anygiven moment. For this reason not only is the trough itself long andrelatively narrow, but it is also provided with means for still furtherreducing the cross-sectional area of the body of milk subjected totreatment at any given point and moment, the means employed for thispurpose being also preferably so constructed as to effect a verythorough agitation or mechanical stirring of the milk as it passesthrough the trough and is subjected to treatment. The means employed byme for effecting this mechanical agitation of the milk and thus bringingthe various particles of the milk as fully as possible under the actionof purifying means, are a series of baflieplates, which will usuallyproject alternately from opposite inner sides of the trough, and thusform an irregular or zigzag channel through which the milk will beforced to flow before it makes its exit from the delivery end of thetrough. By means of such a series of partitions or baflie-plates asthese the milk will be very thoroughly agitated as the result of theresistance of said baffle-plates to the direct flow of the milk in astraight line through the trough, and the milk when thus thoroughlystirred while being subjected to treatment, will be in condition to bemore easily acted upon by the purifying agent or agents than iftraveling in a straight line through the trough. The baflie-plates employed by me may be of any suitable type and construction, thoseillustrated in Fig. 1 being simply partitions projecting at right anglesfrom the inner walls of the trough 2 and being divided into two series,the baffleplates of one group being designated by 3 and those of theother group by 4.

The trough and its various partitions or bafile-plates may be of anysuitable construction and material, these parts being, however,preferably made up wholly of insulating material, such for example asslate, which I have found in practice gives good results. As is obvious,some insulating material is essential in order that electric current maybe applied directly to and passed through the milk for purifying thesame. Electric cur rent from any suitable source of supply may beapplied to the moving stream of milk at practically all points in thelength thereof, but the current used will preferably bean alternatingcurrent, as I have found that purification of the milk can bemorereadily effected by such a current than by direct current, and thetime for carrying out the process and destroying all or substantiallyall bacteria is less than when direct current is used. The current usedmay be taken from any suitable source of supply, such as the ordinarypower mains of a street lighting system, and stepped up by a transformer(not shown) to the desired voltage at which it will be delivered to thefeed-wires 5 and 6, in which may be interposed an ordinary switch, suchas 7, for making and breaking the circuit, and also one or more fuses,such as 8, for the purpose of protecting the apparatus and the milktherein from excessive current. The current employed, 1 have found,should not be less than 300 or 400 volts, in order to obtain the bestresults without unnecessary waste of time, and it may to great advantagebe much higher than this. The amperage of the current will of coursedepend on the voltage, and whatever voltage and amperage are used theyshould not be so great as to unduly heat the milk, a high voltage withlow amperage being preferred in order that bacteria may be destroyedquickly and with very slight heating of the milk.

I prefer to apply the electric current to the milk at the points whereit passes by the respective partitions or bafiie-plates 3 and 4, andeach of these bafiie-plates in this construction has secured to itsinner end a conducting electrode, preferably of copper, con nected withone of the feeders, in this case with the feed-wire Opposite each ofthese electrodes another electrode is preferably secured to the innerwall of the trough, this electrode being also preferably a copper stripor plate. These directly opposing electrodes, affording considerablearea for the emanation of common length shortest lines of current,minimize the cross-sectional density of electric current at these pointsof maximum mechanical current flow, and thus preclude localization ofelectric current as well as avoid excessive heating. The electrodes 9,10, so oppose each other that there may be considerable cross-sectionalarea of straight line currents therebetween, which currents are ofuniform length. The electrodes secured to the baffle-plates aredesignated by 9 and those secured to the walls of the trough by 10. Itis essential that the electrodes be insulated from each other, except asto the substance treated, and in this instance this is accomplished byforming the trough and baffle plates, that is the mountings for theelectrodes, of insulating material. The electrodes 9 are connected byshort conductors 11. with the feed-wire 5, and the electrodes 10 areconnected by short conductors 12 with the feed-wire 6. The electrodes 9and 10 are arran ed in pairs, and the electrodes of each pair are placedat such a distance apart as to permit the current used to pass readilyand assure the destruction of the bacteria contained in the milk passingbetween such electrodes. By this arrangement of the pairs of electrodesit will be seen that the different pairs are connected. in parallelbranches of the same circuit, each of which branches contains a gapacross and through which the current must flow for the purpose ofdestroying the bacteria. By placing these gaps at a large number ofpoints in the length of the trough 2 a corresponding number of points isobtained at each of which the milk Will be subiected to the action ofthe electric current and bacteria therein destroyed. Thus at the pointnearest the source of supply, that is, at the receiving end of thetrough, the milk will have the largest number of colonies of bacteriaper cubic centimeter, and a certain percentage of these colonies ill bedestroyed in passing through the first gap or opening 13 between theelectrodes. The milk passing through the second gap will thus have asmaller num ber of colonies to be destroyed, and the num ber of coloniesper cubic centimeter will decrease at each point at which the milk issubjected to the action of the electric current. In the constructionshown there are seven points at which the electric current passestransversely through a long and relatively narrow moving stream of milk,at each of which points substantially the whole body of milk passingsuch point is subjected to the action of the electric current while inastate of considerable agitation resulting from the resistance opposedto its flow by the alternating or staggered baffle-plates 3 and 4. It isto be noted that the operation is such that the body of the treatedliquid. may not become stagnant near the electrodes or where there isconsiderable electric current therein; that in other words there isrelative movement between the substance treated and the source ofelectri ity completing the circuit, which precludes a separation ofsolids from the milk.

By the time the milk reaches the last pair of electrodes in the seriesall or substantially all of the bacteria propagated in the milk aredestroyed, and it only remains to prevent the contamination of thepurified milk by air bacteria during the delivery of the purified milkinto the receiving vessel or vessels. This may be accomplished byleading the stream of milk to any suitable closed channel or passagewhich is out of contact with the air. In the apparatus shown thedelivery end of the trough 2 is covered for a short distance, in anysuitable manner, as for example by a sheet or plate of glass 14, whichmay be held in position by the frame 15 secured as by screws 1.6 to thetop of the delivery end of the trough. This cover 14 should extend overthe last pair of electrodes of the series, in order that the milk may besubjected to the final purifying treatment after it has passed under thecover 14 and is out of contact with the air. If, during purification,and after the destruction of the bacteria propagated in the milk,bacteria in the air which comes in contact with the purified milk getinto such purified milk, these bacteria will be destroyed by the currentpassing between the last pair of electrodes, and the milk which passesinto the inclosed space at the delivery end of the trough 2 will containno bacteria of any kind. From this inclosed space at the end of thetrough the purified milk may be delivered, without coming in contactwith the air, into one or more suitable receiving vessels or tanks, suchas 17, 18 and 19, connected in series. A. pipe 20 connects the iucloseddelivery end. of the trough with the first receiving tank 17 and iscontrolled by a suitable stop-cocl* 21, by which the delivery of thepurified milk may be regulated or completely out off. The tanks 17, 18and 19 are connected by couplings, such as 22 and 23, in which areinterposed stop-cocks 24 and by means of which both of the receivingtanks 18 and 19 may be cut off from the tank 17, or the two tanks 17 and18 connected while the tank 19 is cut off, or all three of the tanksconnected, as may be desired. In this way either a single tank may befilled, or the first

